Mystery Solved: High-Energy Fireworks Linked to Massive Star Cluster

January 9, 2006: Call it the Bermuda Triangle of our Milky Way Galaxy: a tiny patch of
sky that has been known for years to be the source of the mysterious
blasts of X-rays and gamma rays. Now, a team of astronomers, led by
Don Figer of the Space Telescope Science Institute in Baltimore, Md.,
has solved the mystery by identifying one of the most massive star
clusters in the galaxy. The little-known cluster, which has not been
catalogued, is about 20 times more massive than typical star clusters
in our galaxy, and appears to be the source of the powerful outbursts.

Supporting evidence for the hefty weight of this cluster is the
presence of 14 red supergiants, hefty stars that have reached the end
of their lives. They bloat up to about 100 times their normal size
before exploding as supernovae. This image shows the star-studded
region surrounding the massive star cluster. The bluish cluster is
inside the white box. A close-up of the cluster can be seen in the
inset photo.